Modified pageview buttons to be href buttons rather than form submissions and fixed spacings in widget_calendar edit and add pages

Modified old widget_calendar code to match specs (i.e. turning course into foreignkey, changing html layout)

added announcement-details url and html file, created absolute url function for each announcement post, and created announcement list and detail view classes

implemented assignment-edit.html features + fixed some buttons for assignment-detail.html and assignment-add.html

added to a total of 10 record for widget user and department models, minor edits on widget user edit page to fit specs